In the fabrication of low temperature cofired ceramic circuits (LTCC), ceramic tape serves as the substrate and is cofired to densification with printed circuitry of thick film metallization. If the degree of shrinkage of the metallization is not closely matched to that of the ceramic, the circuit will distort or bow and become unusable. The problem is most severe when (1) the ceramic undergoes crystallization caused by the metallization promoting crystallization of the glasses in the ceramic tape and (2) shrinkage of the metallization composition is different from that of the ceramic tape.
There is a need for a thick film metallization which can be used to fabricate any circuit design and when cofired will result in an undistorted useful LTCC. The present invention utilizes a boron addition to a thick film metallization composition wherein the boron addition minimizes shrinkage of the metallization composition. Therefore, LTCC becomes distortion-free. The metallization compositions are generally known in the art and are described in U.S. Pat. No. 5,782,945 to Gavin, and U.S. Pat. No. 4,101,710 to Sanford and are incorporated herein by reference. Neither patent discloses the use of the composition on a ceramic tape and the shrinkage problem that such a match solves.